Global energy demand is increasing, which is putting pressure on the oil and gas industry to improve the effectiveness of extraction from mature fields and to explore fields that are smaller and located in more challenging environments, including ultra-deepwater environments. The development of subsea oil and gas fields requires specialised equipment that must be robust and reliable to safeguard both the equipment itself and the environment and to make the exploitation of the subsea hydrocarbons economically feasible. The deployment and repair of subsea equipment requires specialised vessels equipped with diving and robotic equipment and so interventions to replace or repair such equipment is generally very expensive.
To monitor the extraction of product from subsea wells, the environmental conditions therein are monitored by pressure and/or temperature sensors located downhole at the base of the wellbore. In addition, wellhead and wellbore equipment to control the flow of product is electronically controlled by command signals from the wellhead. The electronics for interfacing with this subsea equipment to process the received sensor signals and to control the well equipment are generally provided within a subsea electronic module (SEM) that is disposed within a subsea control module (SCM) provided at the wellhead.
The SEM generally provides a plurality of physical cards that support electronic assemblies (such as printed circuit boards, PCBs) arranged in slots connected by a backplane all contained within a robust housing that can withstand the extreme high pressure environment at the subsea wellhead.
The different types of equipment, instruments and sensors provided downhole that are required to be electronically interfaced with for control and sensor data processing are often supplied from a range of different manufacturers and there has been little standardisation of the electronic operation and interfacing protocols. Thus there is required a different card type to perform each specific role for each specific equipment type from each different manufacturer. This leads to a proliferation of hardware requirements and significantly complicates the SEM design and assembly process to fulfil a desired functional specification for the SEM.
As a result, the SEM normally consists of specific electronic assemblies (cards) dedicated to control a certain type of instrument, actuator or other equipment. Often, the cards must be themselves provided by the manufacturer of the equipment. As a result, for each type of equipment, a specific type of card may be necessary for the SEM to be able to communicate with the equipment, leading to a high number of card variants. The functionality of the card is fixed at the time of subsea deployment and the card type is programmed in the centrally stored configuration database of the SEM to allow it to function.
As a result, when planning the production of a SEM, the designing and assembly process can become complicated due to the large number of different card types that are required and for the requirement for an inventory of the range of card types to be maintained. Furthermore, the supply chain and delivery timescales of these proprietary cards from the equipment manufacturers may not be consistent with the requirements of the assembler of the SEM and so the process of designing and assembling the SEM for performing a control and communication role at a specific wellhead can become cumbersome.
European patent application publication number EP 2 282 005 A2 discloses a SEM including a plurality of separate, different electronic circuits provided on a board, each of which is selectable to be in communication with an input to the SEM. In this way, one of the plurality of circuits provided on the card is used, the others go unused. The plural circuits provided on the board each conform to the circuitry of a different sensor arrangement from a different manufacturer. By providing multiple different electronic circuits for different sensor arrangements from different manufacturers on a single PCB, fewer physical card variants are needed. Nevertheless, the flexibility of these co-located cards is limited and the problem posed by card proliferation on SEM design remains.
It is in this context that the present invention is devised.